Handle case when Primary and Replica IP Addresses switch

## Problem

Sometimes, the backend database we are using switches IP addresses between the primary and one of the replicas. We should check whether the database is in read only mode, and if so, then select the actual primary from the list of databases before making a commit

Start by tracing the backend database commit path and the list of configured databases. Check how read-only status is exposed and how the actual primary is selected when primary and replica IP addresses switch. Done means commits use the writable primary after such a switch, with coverage for the read-only case.

Written by the indexing model from the issue text.